The present invention relates to inserts of cemented carbide bodies and rock drill bits preferably for percussive rock drilling.
In U.S. Pat. No. 4,598,779 is shown a rock drill bit that is provided with a plurality of chisel-shaped cutting inserts. Each insert discloses a guiding surface that is relatively sharply connected to cutting edges. A relatively sharp connection is disadvantageous when using cemented carbide. That is, flaking may occur during severe rock drilling due to tension in the connections, such that straight holes may not be achieved in the long run. Also the shape of the known insert is not optimized for maximum wear volume. U.S. Pat. No. 4,607,712 discloses a rock drill bit which has a plurality of cutting inserts. The working part of each insert has a semispherical basic shape, to which has been added extra volume of cemented carbide. However, the prior art insert does not sufficiently support against the wall of the bore such that straight holes may not be achieved. Furthermore, connections between the components of the working part are relatively sharp thereby producing the above-mentioned tensions detrimental for hard cemented carbide. In addition, the spherical basic shape holds a relatively small volume of cemented carbide.